Surgical drain with sensors for monitoring internal tissue condition

ABSTRACT

The present invention is directed to devices and methods of using a surgical drain, and more particularly to a surgical drain having at least one sensor for monitoring and/or recording the condition of the anatomical site or fluid emitted from the site where the surgical drain is placed. The invention may also include modifications of the surgical drain to improve stabilization or immobilization in the proximity of the anatomical site to be monitored.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional PatentApplications 60/445,714, filed Feb. 7, 2003, and 60/453,009, filed Mar.6, 2003, and incorporates the contents in their entirety. Thisapplication is also related to the following co-pending applications,being filed contemporaneously herewith: “Surgical Drain with Sensors forMonitoring Internal Tissue Condition by Transmittance,” attorney docketno. 64693-097; “Surgical Drain with Sensors for Differential Monitoringof Internal Condition,” attorney docket no. 64693-101; “Surgical Drainwith Sensors for Monitoring Fluid in Lumen,” attorney docket no.64693-102; and “Surgical Drain with Positioning and ProtectiveFeatures,” attorney docket no. 64693-103.

BACKGROUND OF THE INVENTION

[0002] 1. Field of Invention

[0003] The present invention is directed to devices and methods of usinga surgical drain to monitor internal tissue condition, and moreparticularly to a surgical drain having at least one sensor formonitoring the condition of a tissue proximate to the surgical drain.

[0004] 2. Description of Related Art

[0005] It is desirable for a physician to know the condition of tissuesor organs (hereafter referred to interchangeably) within the patient'sbody particularly after trauma or surgical manipulation. Since suchtissues may reside under the skin or within a body cavity, a physicianmust invasively inspect the tissue (such as by surgery, includinglaparoscopy), or use indirect measures to assess an organ's condition(such as radiological, blood testing and patient accounts of sensationsof illness or pain). However, these methods can be disadvantageous. Aninvasive examination may cause discomfort and risk of infection to thepatient, and the information obtained either through direct inspectionor indirectly via blood or radiological analysis, may be relevant onlyto the time at which the procedure is performed, and examination mayrender only indirect information about the physiological condition ofthe organ.

[0006] Monitoring of organ function can be important after surgeriessuch as organ transplantation, resection, cryosurgery and alcoholinjection. Surgical complications, such as vascular complications, maydisrupt adequate oxygen circulation to the tissue, which is critical toorgan function and survival. Following liver surgery, for example, aphysician may draw patient blood to determine the condition of the organby measuring liver enzymes (such as transaminases) and clotting factors(such as prothrombin). Unfortunately, these blood tests reflect livercondition only at the time the blood sample is drawn, and changes inthese laboratory values can often be detected only after significantorgan damage has already occurred, permitting a limited opportunity forintervention by the physician to improve the condition of the organ orfind a replacement organ in case of transplantation for the patient.

[0007] Other methodologies have been used to assess internal tissueconditions. For example, (1) imaging and Doppler techniques, (2) opticaltechniques, and (3) thermodilution have been used to measure tissueoxygenation and/or perfusion. However, these techniques can be difficultto successfully apply to continuous monitoring of organ condition, andmay provide only qualitative or indirect information regarding acondition, and/or may provide information about only a small segment ofan organ.

[0008] Imaging and Doppler Methods. Angiography may be used fordetermining the location and extent of blood flow abnormalities in majorhepatic vessels, such as hepatic artery or portal vein stenoses andthromboses. Similarly, Doppler sonography may be used for the evaluationof blood flow in the hepatic artery and the portal vein. These methodscan lack the sensitivity and the resolution necessary for assessinghepatic microcirculation. Contrast sonography has been applied forqualitative assessment of blood perfusion in the microvasculature, butits potential for quantitative measurement is still unclear. Althoughsonography can be performed at bedside, it is neither sensitive norspecific, and does not indicate the actual tissue oxygenation. It isusually used as a screening for the more invasive angiography.Angiography is still a preferred clinical standard in determining vesselpatency for any organ such as blood flow abnormalities in major hepaticvessels, such as hepatic artery or portal vein and may visualizestenosis or thrombosis in these and other vascular structure. This testhowever is invasive and requires the injection of contrast material withits side effect of allergic reaction, kidney failure and fluid overload.The test cannot be performed at bedside (as in Doppler Ultrasonography)and requires moving critical ill patient to the radiology suite, and theside effects are also higher in these sick patients.

[0009] Other imaging methods, such as Spiral Computer Tomography (CT),three-dimensional magnetic resonance, angiography and radionuclidescintigraphy using Technetium 99 m sulfur colloid may be used to assessblood flow to organs such as the liver following liver transplantation.However, these methods may not be sufficiently sensitive to obviateangiographic assessment, as described above. Further, these methods canalso be limited in their ability to measure blood perfusion inmicrovasculature of the tissue. Although blood may be circulating tolarge vessels, it is oxygenation and perfusion at the capillary level,which often maintains the health of the entirety of the organ. By thetime larger vessels are visibly impaired, the organ may have alreadyundergone significant tissue damage. Further, these methods may beinvasive in requiring the infusion of dye to which patients may react.Finally, for each dye injection, the organ condition may be assessed fora given interval. If further monitoring is needed, additional dyeinjection and repeated imaging may be required.

[0010] Laser Doppler flowmetry (LDF) has been used to measure blood flowin the hepatic microcirculation, but may not be able to provideinformation about the tissue oxygenation or blood content. LDF is alsolimited in its application due to the short depth of penetration and thelarge spatiotemporal variations of the signal obtained. Therefore, thistechnique may not reflect information regarding a broad geography of thetissue, and large variations may occur in recordings from differentareas, in spite of tissue conditions being similar between the regions.

[0011] Thermodilution. Thermodilution technology has also been used formonitoring tissue perfusion. One example is the Bowman perfusionmonitor, which uses an invasive catheter probe to measure hepaticperfusion. The probe may be inserted into the liver and a thermistor inits tip may be heated to remain slightly above tissue temperature. Thelocal perfusion may be estimated from the power used in heating thethermistor to few degrees above tissue temperature to induce localdilation of the blood vessels. This can lead to a false perfusionmeasurement that is higher than the actual perfusion away from theprobe. The latter source of error may not be corrected by calibrationbecause the degree of vasodilation per temperature rise may vary betweenpatients and may depend on many factors including administered drugs.

[0012] Thermodilution techniques may also be disadvantageous at least inrequiring the insertion of catheter probes into an organ, which canbecome impractical when multiple probes are to be used.

[0013] Perfusion detection techniques such as LDF and thermodilutionhave an additional common inherent limitation. These methods may notmeasure tissue oxygenation, which is more relevant than perfusion indetermining tissue viability. Perfused tissue can still suffer ischemia,oxygen deprivation, depending on the oxygen demand by the tissue versusits availability in the blood. For example, the liver has a dual bloodsupply from the hepatic artery and the portal vein. The blood flowingfrom the portal vein into the liver carries much less oxygen to thehepatic tissue than that from the hepatic artery. An occlusion of thehepatic artery would not cause a significant drop the hepatic perfusion,however, it would cause a drastic drop in the oxygenation. Hence,monitoring the hepatic perfusion only would be a misleading measure ofischemia. Further, this critical demand-availability balance can beeasily disturbed due to immunogenic and/or drug reactions, thereforemonitoring of oxygenation levels is important in monitoring tissuecondition.

[0014] Optical Methods. Conventional optical techniques for thedetection of tissue ischemia include fluorescence and transmissionmethods. Ischemia leads to anaerobic respiration and the accumulation ofthe reduced nicotinamide coenzyme NADH. The concentration of NADH may bedetected optically because it is autofluorescent and has peak excitationand emission wavelengths at about 340 nm and 470 nm, respectively.Therefore, the fluorometric properties of NADH can be used to monitorand quantify this marker of ischemia.

[0015] However, this technique may not have been applied clinically dueto several concerns. First, the fluorescence of NADH can be stronglymodulated by the optical absorption of tissue hemoglobin, and theabsorption of hemoglobin varies with its state of oxygenation, which cancomplicate the analysis of the data. These modulations can mask theactual intensity of NADH fluorescence thereby causing inaccuracies inthe evaluation of ischemia. Further, this method may be disadvantageousat least in that repeated exposure of the tissue to ultraviolet lightresults in photobleaching of the tissue. Therefore, it may not bepossible to continuously monitor the same position on the organ for aprolonged period of time (i.e., more than 24 hours). Finally, the abovemethod is only an indirect evaluation of tissue ischemia, as it relieson monitoring abnormalities in the concentration of NADH and may resultfrom other conditions such as generalized sepsis or hypotension.

[0016] Optical transmission methods involve the use of visible and/ornear-infrared radiation to measure the absorbance of blood in a tissuebed and determine the oxygen saturation of hemoglobin. A commontransmission technique is pulse oximetry where red and infrared lightfrom light emitting diodes is transmitted through the tissue, usually afinger or ear lobe, and detected by a photodiode. The oxygen saturationof hemoglobin can be estimated by measuring its optical absorption atpredetermined wavelengths that allow the maximum distinction betweenoxyhemoglobin and deoxyhemoglobin. Researchers have used lasers toilluminate one side of the kidney and detected the transmitted light onthe opposite side using a photomultiplier. For example, Maarek et al.,SPIE, Advances in Laser and Light Spectroscopy to Diagnose Cancer andOther Disease, 2135:157-165, 1994. A major disadvantage of suchtechniques is the invasive nature of the procedure to place a tissuesample between the light source and the detector for a singlemeasurement.

[0017] Intra-abdominal pressure following major surgery or trauma (suchas a car accident, gun shot wounds, combat, or earthquake injuries) mayrise to extremely high levels due to tissue edema secondary to theinjury, especially following multiple blood transfusions, severe shockor inflammatory responses.

[0018] An increase in pressure may lead to severe organ dysfunction,such as kidney failure and acute respiratory failure due to lungcompression through the diaphragm. The increased pressure in the abdomenmay also lead to a decrease in the venous returns to the heart,therefore, affecting the cardiac output and the perfusion to allorgans/tissues leading to a decrease in oxygen delivery.

[0019] Early detection of critical intra-abdominal pressure may becorrected by several interventions, including sedating the patient oropening of the abdomen. Prompt restoration of proper intra-abdominalpressure can reverse the consequences described above. However, once acritical point is reached, organs may suddenly fail, which may beirreversible in certain conditions and lead to rapid deterioration ofmultiple organs and potentially death.

[0020] A current method of monitoring intra-abdominal pressure followingmajor surgery or trauma relies on indirect measurement of intra-organpressure such as the bladder or the stomach pressure. These methodsrequire direct operator intervention and are done only intermittently ata specific timing, such as every 1 to 4 hours, or if the patient showssigns of deterioration.

[0021] Current methods of measuring abdominal pressure may carrysignificant errors due to direct personal intervention, lack ofreproducibility and challenges related to the injury itself. Forexample, a large hematoma or pelvic fracture may affect the bladderpressure directly without relation to the overall intra-abdominalpressure.

[0022] As discussed above, each of these methods has significanttechnical disadvantages to monitoring tissue condition. Further, each ofthese methods can also be cumbersome and expensive for bedside operationdue to the size of the apparatus and cost associated with staffadministering these methods, and unsuitable for continuous monitoring oftissue conditions.

[0023] Therefore, it is desirable to have a device and methods to aidphysicians in predicting problems and complications associated withinternal trauma or surgery. It is desirable to have a device which ispositionable and removable with relatively minimal effort, minimallyinvasive and causes minimal discomfort for the patient, providescontinuous current information about tissue or organ condition, providesdirect information about tissue or organ condition, and/or providesfeedback on the effects of interventions, such as medications or otherprocedures to improve tissue or organ condition.

BRIEF SUMMARY OF INVENTION

[0024] In one embodiment of the invention, a surgical drain may be usedfor postoperative monitoring of the condition of a tissue and/or organ,generally or a transplanted organ, more specifically.

[0025] In one embodiment of the invention, a surgical drain may be usedto provide continuous intraoperative and/or postoperative information onthe physiological condition of a tissue including perfusion and/oroxygenation.

[0026] In one embodiment, a surgical drain may be configured for ease ofapplication by a physician, as well as ease of removal when monitoringis no longer required.

[0027] These, as well as other objects, features and benefits will nowbecome clear from a review of the following detailed description ofillustrative embodiments and the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0028]FIG. 1A is a schematic diagram of one embodiment of a surgicaldrain in use having at least one sensor; FIG. 1B is a schematic diagramdepicting one embodiment of a surgical drain; FIG. 1C is a schematicdiagram of one embodiment of the surgical drain in use having aplurality of sensors.

[0029]FIGS. 2A & B are each schematic diagrams each of one embodiment ofthe invention.

[0030] FIGS. 3A-F are schematic diagrams depicting views of embodimentsof the surgical drain according to the invention. FIGS. 3A-F are bottomviews of embodiments of a surgical drain; FIGS. 3D & E are end views ofembodiments of a surgical drain.

[0031]FIGS. 4A & B are schematic diagrams each of a side view of oneembodiment of a surgical drain.

[0032]FIGS. 5A & B are schematic diagrams of a top and bottom plan viewof one embodiment of a surgical drain, respectively; FIG. 5C is aschematic diagram depicting a cross-sectional view of one embodiment ofa surgical drain.

[0033]FIG. 6A is a schematic diagram of a side view of one embodiment ofa surgical drain; FIG. 6B is a schematic diagram depicting across-sectional view at A—A of the embodiment shown in 6A.

[0034]FIG. 7 is a schematic diagram of one embodiment of a surgicaldrain in use.

[0035]FIGS. 8A & B are a schematic diagrams each of an alternateembodiment of a multifiber connector.

[0036]FIG. 9 is a schematic diagram of one embodiment of a surgicaldrain with wireless connectivity.

[0037]FIG. 10 is a flow diagram of one embodiment of a monitoring systemof the invention.

[0038]FIG. 11 is a schematic diagram of one embodiment of a multiplexercircuit.

[0039] FIGS. 12A-D are schematic diagrams each depicting one embodimentof a display.

[0040]FIGS. 13A & B and 13E & F are schematic diagrams ofcross-sectional views of embodiments of surgical drains having aninflatable chamber. FIGS. 13C & D are schematic depictions of side viewsof one embodiment a surgical drain having an inflatable chamber andinflation devices. FIG. 13G is a graphic representation of reflectanceintensities received from the sensing system.

[0041]FIG. 14A is a schematic depiction of a bottom view and FIG. 14B isa schematic depiction of a side view of one embodiment of a surgicaldrain having protrusions thereon.

[0042] FIGS. 15A-F are schematic diagrams of embodiments of surgicaldrains modified to improve stability of the drain relative to the tissuemonitored.

[0043]FIG. 16 is a modified distal end of a fiber collecting orreceiving energy of one embodiment of a surgical drain.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0044]FIG. 1A is a schematic diagram depicting one embodiment of asurgical drain in use having at least one sensor. As shown in FIG. 1A,the device may include a surgical drain 10 configured for implantationwithin the patient's body proximate to a tissue and/or organ 100 ofinterest having at least one sensor or receiver 12.

[0045] The surgical drain 10 may include one or a plurality of sensors12 in communication with a monitor 14, such as via a data cable 16. Themonitor 14 may also include a display 18 configured to depictinformation obtained from the sensor 12. The surgical drain 10 may be incommunication with a tube 40 having a conduit lumen 42, such that thefluids passing from the body in the drain lumen 32 may be transportedout of the body 102 via the conduit lumen 42. The tube 40 may be formedintegrally or as separate piece attached to the surgical drain 10.

[0046]FIG. 1B is a schematic diagram depicting one embodiment of asurgical drain 10. As shown in FIG. 1B, the surgical drain 10 may have adrain length 20, extending from the drain distal end 22 to the drainproximal end 24. The surgical drain 10 may have an outer surface 26 anda drain inner surface 28 and a drain wall 30 extending from the drainouter surface 26 to the drain inner surface 28. The drain wall 30 may bein any cross-sectional shape, such as rectangular, round, oval. Thesurgical drain 10 may include a drain lumen 32 extending the drainlength 20, and the drain lumen 32 may be open or closed at the draindistal end 22. The surgical drain 10 may include at least one or aplurality of drain holes 34 extending through at least one location onthe drain wall 30. The surgical drain 10 may include approximately adrain upper surface 36, and a drain lower surface 38, and may includedrain holes 34 on the drain upper surface 36 and/or lower surface 38.

[0047] A surgical drain 10 may be in the form of an elongated conduitand a flexible drain wall 30, having a substantially flat cross sectionhaving at least one internal rib 128 as shown in FIG. 5C) within thedrain lumen 32, and a pattern of drain holes 34 along at least a portionof the drain length 20, such as along at least half of the drain lengthor along the entire drain length 20. The conduit may be in the form of alinear conduit or any shape, including but not limited to circular,square or triangular form.

[0048] An internal rib 128 may act to prevent the drain wall 30 fromcollapsing into the drain lumen 32 even when the surgical drain 10 issubject to a very high vacuum and/or strong lateral compression forcesdue to body movements of the patient and the healing process at thedrainage site. An internal rib 128 may also wipe back and forth acrossthe opposite drain wall 30 to keep the conduit lumen 32 and drain holes34 clear when the drain walls 30 are moved laterally relative to oneanother. An internal rib may extend partially into the drain lumen (asin FIG. 5C) or across the entire lumen (as in FIG. 6B), for example.

[0049] The surgical drain 10 may be made of any material suitable forimplantation within the body 102. The material may be selected so as tobe minimally allergenic, for example. A surgical drain 10 which may beused in this invention may include a standard surgical drain. By way ofexample, the surgical drain 10 may be of a biocompatible silicone, latexrubber, polyvinyl chloride (PVC) or teflon of any color, and may beentirely or partially transparent. This may be advantageous in thattransmitting and receiving elements may be positioned within the drainwall. In one embodiment, the optical fibers 44 may transmit light to afiber distal aperture proximal to the surgical drain 10 and irradiate atissue 100, and a second optical fiber distal aperture may collect thereturned light via an optically transparent window in the drain wall 30.

[0050]FIG. 1C is a schematic diagram depicting one embodiment of asurgical drain 10 in use having a plurality of sensors 12. The surgicaldrain 10 may include electrical transmitters and/or sensors, and/orfiberoptic transmitters and/or sensors. A corresponding wire or fiberfrom each sensor 12 may run along the drain length 20 and exit thesurgical drain 10 as a data cable and/or multi-fiber bundle 16 thatcouples the sensor 12 to a monitoring system 14. Examples of connectors62 which may be used to couple the sensor to the monitoring system aredescribed with reference to FIGS. 8A & B below.

[0051]FIGS. 2A & B are schematic diagrams of each of one embodiment ofthe invention. The surgical drain 10 may include at least one or aplurality of sensors 12. As shown in FIG. 2A, the surgical drain 10 mayinclude a plurality of sensors 12 spaced along the drain length 20 topermit the monitoring of different locations of a tissue 100 A, B & C tobe monitored. As shown in FIG. 2B, the surgical drain 10 may have aplurality of drain branches 10 a/b to accommodate monitoring largerwounds, tissue beds or tissues 100. Finally, in one embodiment, aplurality of separate surgical drains 10 may be used to monitor a singleorgan or a plurality of organs 100 at the same time.

[0052] The surgical drain may include a sensing system configured tosense a physiological property of a tissue 100 proximate to a surgicaldrain 10. In some embodiments, the sensing system may include sensors 12which are positioned proximate to the surgical drain 10 and tissue. Insome embodiments, transmitting elements 48 and receiving elements 12 maybe configured to deliver energy and receive energy, for transmission toanother portion of the sensing system to sense a physiological propertyof a tissue. The energy may include, but is not limited to, light, heatand ultrasound. It is to be understood that sensor 12 may refer toeither a sensor, such as an electrical sensor, or a receiving elementsuch as a fiberoptic proximate to the surgical drain 10. The sensors 12may be positioned proximate to a tissue 100 for which monitoring isdesired, and the sensors 12 may be configured to receive and/or detectparameters regarding the condition of the tissue 100, fluid proximate tothe tissue or flowing into the surgical drain 10 therefrom. The surgicaldrain 10 may include at least one sensor 12 in contact with the surgicaldrain 10. For example, the sensor 12 may be on the drain outer wallsurface 26, drain inner wall surface 28 or within the drain wall 30. Thedrain wall 30 may be modified to include a groove 46 to accommodate thesensors 12, transmitter 48 and/or wires/fibers 44 extending therefrom.

[0053] The sensor 12 may be situated such that at least a portion of thesensor 12 is in contact with the monitored tissue 100 or in proximity tothe tissue 100, or in contact with interstitial fluids therefrom so asto probe the condition of the adjacent tissue.

[0054] A sensor 12 may be configured to detect physiological parameters,which permit the measurement of tissue oxygenation, perfusion,haemoglobin content, color, temperature, pressure, pH, respiratorycoenzymes (such as NADH), local exogenous drug levels, mechanicalproperties (such as turgidity) and biochemical composition of the fluidwithin the surgical drain (such as hemoglobin, puss, bile, intestinalcontents, etc.).

[0055] By way of example, pH sensors 12 may be used to detect changes inion concentration in fluids surrounding a tissue 100 or within a drainlumen 32. For examples of pH sensors that may be useful in thisinvention, see U.S. Pat. No. 5,916,171 to Mayviski, herein incorporatedby reference.

[0056] In one embodiment, a temperature sensing system may be used todetect the temperature of a tissue 100. For example, a fiberopticthermometer may be used. The fiberoptic may transmit an excitation lightpulse to the fiber distal end in proximity to a tissue 100, causing itto fluoresce. The fiber distal end may include a nonconductive phosphortip. The fluorescent signal may be transmitted back to a photodetectorby the same fiber. The fluorescent decay time may be measured by amultipoint digital integration decay curve, used to correlate the decaycurve with a temperature value.

[0057] In one embodiment, a pressure sensing system may be used todetect the pressure within a body cavity, such as the abdominal cavity.For example, a fiberoptic pressure sensor may be used, and may include apressure sensing element such as an optical interferometer at a distaltip of a fiber, and interferometric integration may be used to sense andmonitor pressure over time. For examples of integration methods, seeU.S. Pat. Nos. 5,392,117 and 5,202,949, herein incorporated byreference.

[0058] FIGS. 3A-F are schematic diagrams depicting views of embodimentsof the surgical drain according to the invention. FIG. 3A depicts abottom view of one embodiment of a surgical drain 10 including at leastone sensor 12 proximate to the drain lower surface 38. The surgicaldrain 10 may further include at least one transmitter 48 for deliveringenergy, such as light, including white light, to the monitored tissue100, in the proximity of the at least one sensor 12. The surgical drain10 may further include a plurality of pairs of transmitters 48 andsensors 12 located along the surgical drain length 20 so as to detectinformation from different regions of the organ 100, as shown in FIG.1C, for example.

[0059] By way of example, as shown in FIG. 3A, a sensor 12 in proximityto a transmitter 48 may be used to collect derived energy, including thereflectance or diffuse reflectance from, or transmitted energy throughthe tissue 100 monitored.

[0060]FIG. 3B depicts a bottom view of one embodiment of a surgicaldrain 10 including at least one sensor 12 positioned in a groove 46formed in the surgical drain wall 30. The surgical drain 10 may furtherinclude a transmitting element 48, and/or at least one or a plurality ofdrain holes 34 along the drain length 20.

[0061]FIG. 3C depicts a bottom view of one embodiment of a surgicaldrain 10 including at least two sensors 12 a/b, spaced at a distancefrom a transmitter 48 on the drain lower surface 38. In one embodiment,the configuration may be used such that at least one transmitter 48transmits energy and the sensors 12 a/b receive derivative energy todetect different physiological parameters of the tissue 100, such asperfusion, oxygenation and temperature. The configuration may be used tomeasure the same parameter, and may permit the measurement of energyattenuation over distance between the transmitter 48 and the sensors 12a/b.

[0062]FIG. 3D depicts an end view of one embodiment of a surgical drain10 including at least one sensor 12 positioned within the drain wall 30.This configuration may allow the positioning of longer sensors in thedrain wall and may avoid the need for thicker drain walls. In addition,this configuration may allow a farther placement of a sensor 12 from atransmitter 48 to avoid saturation. This may be a particularly usefularrangement when using high output (e.g., luminance) transmitters fordeeper range detection. Positioning of sensors 12 in different areas ofthe drain wall 30 may permit the collection of information from avariety of tissue locations 100. Information from each location may becompared to obtain differential parameter measures.

[0063]FIG. 3E depicts one embodiment of the surgical drain 10 which mayinclude at least a pair, including a transmitting element 48 and asensor 12 positioned at different positions of the drain wall 30, suchas within approximately opposite sides of the drain lumen 32. In oneembodiment, the transmitting element 48/sensor 12 pair may act as an insitu spectrophotometer to detect substances within the drain lumen 32between the transmitting element 48/sensor 12. Variation of thecomposition of fluid along sequential pairs of sensors 12 along thedrain length 20 may yield information about the source or condition ofthe fluid. For example, the wavelength dependent attenuation oftransmitted radiation by the fluid flowing in the drain lumen may beused to determine whether blood, puss, bile, intestinal contents, and/ora mixture of all are present, according to standard spectrophotometrictechniques. The contents of the drain lumen may be is indicative of thecondition, including the healing progress of the tissue.

[0064]FIG. 3F depicts one embodiment of the surgical drain 10, which mayinclude at least one sensor 12 positioned at least partly within thedrain lumen 32. In one embodiment, the sensor 12 may act to detect thecomposition or the mechanical properties of fluid flowing in thesurgical drain lumen 32.

[0065]FIG. 4A is a schematic diagram depicting a side view of oneembodiment of a surgical drain 10, which may include a sensor 12embedded in the drain wall 30 and a transmitting element 48 to beinserted into the organ 100. The sensor 12 and transmitting element 48may be fiberoptic or electrical, and the distal ends of each may beoriented such that energy emitted from the transmitting element 48 maybe substantially received by the sensor 12. For example, as shown inFIG. 4A the sensor distal end 12 may terminate at a perpendicular to thesurgical drain outer surface 26 and the transmitting element distal end48 may be angled such that the sensor receives energy emitted from thetransmitting element 48 distal end. In one embodiment, the distal end ofthe sensor 12 and the transmitting element 48 may be coaxially aligned.In one embodiment, the surgical drain 10 may include a transmittingelement 48 embedded in the drain wall 30, and a sensor 12 to be insertedinto the organ 100. In one embodiment, a housing 50 with a housing lumen52 may be opposed to or encompass the transmitting element 48 or sensor12 that is being inserted into the organ 100 to provide structuralsupport. The housing 50 with a housing lumen 52 may be a hollow needlemade of a biologically compatible material. The housing 50 mayadvantageously serve as an anchor to attach and/or immobilize thesurgical drain 10 relative to an organ 100.

[0066]FIG. 4B is a schematic diagram depicting a side view of oneembodiment of the invention, which may include optical transmissionsensors composed of two needle shaped fiberoptics 12/48 for insertioninto a monitored tissue 100. For example, as shown in FIG. 4B thetransmitting element distal end 48 and sensor distal end 12 may beangled such that the sensor 12 receives radiation emitted from thetransmitting element 48. In one embodiment, the transmitting element 48and sensor 12 may each be opposed to or encompassed by a housing 50 witha housing lumen 52 to provide structural support. The housing 50 with ahousing lumen 52 may be a hollow needle made of a biologicallycompatible material. The housing 50 can advantageously serve as ananchor to attach and immobilize the drain 10 on the organ 100.

[0067] As shown in FIG. 16, in one embodiment, to enable a fiber toirradiate energy at about 90 degrees, the fiber distal end may bepolished at about a 42-degree angle (α) to its axis. Further, glassferrule caps may be placed over the polished end. In use, the light maybe reflected on the polished end, and be emitted at about 90 degrees tothe fiber axis 132.

[0068] In one embodiment, a fiber collecting or receiving energy may beprepared using a similar process.

[0069] In these configurations, for example, light emitted from atransmitting element 48 may be transmitted through a tissue thickness 54to a sensor 12. Using standard transmission, reflection and/orfluorescence spectroscopy techniques, the transmitted light may be usedto measure physiological information including, but not limited totissue oxygenation, perfusion, coloration, and drug concentration.

[0070]FIGS. 5A & B are schematic diagrams depicting a top and bottomplan view of one embodiment of a surgical drain 10. Optical fibersand/or the lead wires 44 that may connect the sensors 12 and thetransmitters 48 may be evenly distributed along the drain surfacelengthwise to prevent the mechanical twisting of the drain wall 30. Thismay be advantageous at least to maximize contact between the sensors 12and the tissue 100.

[0071]FIG. 5C is a schematic diagram depicting a cross-sectional view ofone embodiment of a surgical drain 10. In one embodiment of theinvention, the surgical drain 10 may include at least one pair ofsensors 12 a/b positioned approximately on opposite sides of the drainwall 30. The surgical drain 10 may also include a plurality of pairs ofsensors 12 a/b, 12 c/d, 12 e/f positioned at different locations alongthe drain length to detect information from different positions alongthe drain length 20, such as shown in FIG. 6A.

[0072]FIG. 6A is a schematic diagram of a side view of one embodiment ofa surgical drain; and FIG. 6B is a schematic diagram depicting across-sectional view of one embodiment of a surgical drain. In oneembodiment of the invention, the surgical drain 10 may include at leastone pair of sensors 12 a/b positioned proximate to different surfaces ofthe surgical drain 10. The surgical drain 10 may also include aplurality of pairs of sensors 12 a/b, 12 c/d, 12 e/f positioned atdifferent locations along the surgical drain length to detectinformation from different positions along the drain length 20.

[0073] As shown in FIG. 6B, in one embodiment, the surgical drain 10 mayhave a drain width 56 of about 15 mm, and a drain height 58 of about 6mm, a drain length 20 of about 200 mm, a drain hole diameter 34 of about1.5 mm, and a drain lumen height and width of about 4 mm. The surgicaldrain 10 may include a plurality of lumens 32; and fibers/wires 44 toand/or from the transmitting elements 48 and/or sensors 12 may beoriented within the surgical drain 10, such as in an internal rib 128.In one embodiment, a sensor 12 may be embedded in the drain wall 30.This may be advantageous at least in facilitating the use of additionalmodifications to drain wall 30 or outer surface 26, such asstabilization devices and mechanisms for increasing contact betweentissue and sensors, described below.

[0074]FIG. 7 is a schematic diagram depicting one embodiment of a drainin use. In one embodiment, sensors 12 may be placed on opposite sides orproximate to sides of the surgical drain 10 such that the sensor pairs12 a/b may be used to acquire differential measurements betweendifferent organs/tissues positioned in the proximity of sensors pair 12a/b. For example, as shown FIG. 7 a surgical drain 10 may be positioned,such that the drain lower surface 38 is proximate to an organ to bemonitored 100, and the drain upper surface 36 is proximate to anadjacent tissue. Therefore, sensor pairs 12 a/b may be positioned tomeasure a parameter differentially between the monitored organ 100 andthe adjacent tissue. These differential measurements may improve theaccuracy of the measurements/diagnosis, such as in monitoring forcomplications in hepatic perfusion. For example, a lower than normaloxygenation of the liver may not be indicative of problems in thehepatic perfusion because the oxygenation of the whole body may be lowerthan normal due to respiratory and/or circulatory problems. However, ifthe oxygenation levels of the liver are lower than normal while theadjacent tissues are at normal oxygenation levels, then this is a realindication of reduced hepatic perfusion.

[0075] Any type of sensors (such as oxygenation, perfusion, pH,temperature, color) may be used in a differential mode measurement, suchas described above. The sensor 12 type used may be selected so as tomaximize the detection of the desired physiological parameter, maximizebiological compatibility with the patient's tissues or other componentsof the device, and to minimize any risk of electrocution or the like.

[0076] In one embodiment, the device may be configured to detect thecolor of an organ 100. The surgical drain 10 may use a single fiber, ormay include at least one transmitting element 48 and at least one sensor12. The transmitting element 48 may be a fiberoptic 44 having a distalend configured to deliver light from a light source to the organ 100.The light may be reflected from, diffusely reflected from or transmittedthrough at least a portion of the organ 100 in the proximity of thetransmitting element distal end 48. The sensor 12 may be a fiberoptic 44having a distal end configured to collect light having a spectralpattern reflected, diffusely reflected or transmitted through the organ100, and transmit the spectral pattern to a photodetector or processingsystem 80. The color may be extracted from a wavelength spectrum usingstandard wavelength to RGB conversion techniques.

[0077] The oxygenation of an organ may be determined by measuring theoxygenation of the hemoglobin within a tissue. The spectralcharacteristics of hemoglobin are dependent on its state of oxygenation.The oxygenation of the organ 100 may be determined by measuring thespectral characteristics of hemoglobin using a similar sensor 12, asdescribed above.

[0078] The monitoring system 14 may include a processing system 80 forconverting the spectral pattern information to a color, which may bepresented to a physician on a display 18. The processing system 80 mayalso convert the spectral pattern information to a color index number,which may be presented to a physician on a display 18. The system mayalso include data of normal colors and color indexes for automatic ormanual comparison so that a tissue abnormality may be noted.

[0079] Determining the physiological conditions, such as color and/orcolor index of the tissue, may be advantageous at least in that thephysician may determine from the color of the tissue the general healthof the tissue, including whether the tissue is adequately oxygenatedand/or jaundiced. Further, the monitoring function is advantageous inthat it may be continuous or at intervals selected. Further, themonitoring function is advantageous in that is may be minimally invasiveand does not require opening the patient to assess the tissue condition.

[0080] In one embodiment, diffuse reflection may be used to determinethe oxygenation level of at least a portion of an organ 100. This methodmay be advantageous at least in that information about the internalportion of the organ 100 may be obtained, without penetrating thesurface of the tissue with a sensor 12 or a transmitting element 48.

[0081] In one embodiment, the device may be configured to detect thetemperature of the monitored organ 100. In one embodiment, the devicemay include a fiberoptic temperature sensor as described above inproximity to the surgical drain 10. The temperature sensor 12 maytransmit the light for information processing. A processing system 80may convert the phosphorescence decay-time to a temperature value whichmay be presented to a physician on a display 18. The system may alsoinclude data of normal temperatures for automatic or manual comparisonso that an abnormality may be noted. Determining the temperature of theorgan 100 is advantageous at least in that the physician can determinefrom the temperature the general health of the tissue including whetherthe tissue is being properly perfused after transplant as improperlyperfused tissues may decrease in temperature, for example. A temperaturesensor 12 may be of any type other than fiberoptic includingthermistors, thermocouples and resistance temperature detectors (RTD's),for example.

[0082] The system may acquire simultaneous differential measurementsfrom along the drain length or between the different tissues betweenwhich the surgical drain 10 is positioned. Measurement of a givenparameter simultaneously from adjacent normal organs/tissues (e.g.,abdominal wall) and from the organ/tissue of interest suffering problems(e.g., the liver) can provide a control or reference value. This controlor reference value can be used as a comparison factor to improve theaccuracy of the parameter measured from the organ/tissue of interest100.

[0083] In one embodiment, the device may be configured to detect therespiratory coenzyme NADH levels from the monitored organ 100.Fluorescence spectroscopy may be used to measure the fluorescence ofNADH which has a peak emission at 470-nm and to detect its concentrationin the tissue 100.

[0084] In one embodiment, the device may be configured to detectconcentrations of exogenous drugs within the tissue 100 or fluid in thedrain lumen 32. For example, drugs (such as chemotherapeutic agents) mayauto-fluoresce or may be coupled with a fluorescing tag having aselected peak emission, which may be detected by fluorescencespectroscopic methods.

[0085] In one embodiment, the device may be configured to detectpressure. In .one embodiment, the surgical drain 10 may includefiberoptic pressure sensors as described above.

[0086] The surgical drain 10 may include at least one or a plurality ofsensors 12 in communication with a monitoring system 14, such as via adata cable 16, such as shown in FIG. 1A. Wires and/or fibers 44 may bebundled together towards the surgical drain 10 proximal end and exit thesurgical drain 10 within a sheath.

[0087] In one embodiment, the surgical drain 10 may include opticalfibers 44 a/b and a multifiber connector 62 may be an optical fiberopticconnector, which joins each fiber 44 a to a complementary fiber 44 b inthe monitoring system 14 to establish optical continuity. FIG. 8A is aschematic depicting a side view of one embodiment of an opticalconnector 62 that may be constructed to minimize the distance betweenthe apertures of the corresponding optical fibers 44 a/b. The regionwhere the fiber apertures meet may be filled with an index-matchingsubstance 64, such as optical gel to optimize the optical continuitybetween the corresponding fibers 44 a/b. The optical gel may fill theair gap between corresponding optical fibers and hence improve lighttransmission by decreasing the back reflection that may occur at an airinterface due to mismatch in the refractive index. The connector 62 maybe configured so as to have a complementary shape to a receptor 66. Theconnector 62 and receptor 66 may include complementary locking members68 a/b to maximize the meeting of the apertures of the correspondingoptical fibers and prevent inadvertent separation between thecomponents.

[0088]FIG. 8B is a schematic depiction of one embodiment of a multifiberconnector 62, which may be used in a surgical drain 10 including lightsources 60. In one embodiment, at least one light emitting diode (LED)may be used as a light source 60, such as when low power consumption isdesirable. The LED may be of the white, multi-wavelength, ormonochromatic type. An LED-block 70, such as shown in FIG. 8, may beused to couple at least one LED to a transmitting element 48, such as anexcitation optical fiber 44 and hence minimize light losses at themultifiber optical connector 62. In one embodiment, electricalconnectors 72 may be used to drive LEDs 60 in a LED-block 70, while theoptical connectors 74 may be used to guide the collected optical signalsfrom sensors 12 to a monitoring system 14.

[0089]FIG. 9 is a schematic diagram depicting one embodiment of asurgical drain with sensors and wireless connectivity. In oneembodiment, the device may include a monitor 14 in communication withthe sensors 12 of the surgical drain 10. The monitor 12 may be directlyaffixed to the end of the surgical drain 10 and/or tube 40, and mayutilize an antenna 78 to receive command signals to activatetransmitting elements 48 and/or transmit data obtained from the sensors12 to a receiver 76. If the monitoring system 14 includes an antenna 78,the antenna 78 may be positioned such that it runs longitudinally alongthe drain tube 40.

[0090] In one embodiment of the invention, the device may comprise asurgical drain 10 in communication with a monitoring system 14 that mayinclude a processing system 80, a display 18, device(s) to drive thefrequency and/or magnitude of signals to transmitting elements (such asa lamp multiplexer 82) and/or receive and detect information fromsensors 12 and/or a device to record information from a sensor 12associated with the surgical drain 10 over time. The monitoring system14 may be configured so as to continuously obtain information regardingthe condition of the organ or obtain information only at preselectedintervals or on demand from a physician. In one embodiment of theinvention, the monitoring system may include a recorder 108. Therecorder 108 may store acquired information for later retrieval andreview. The recorder may be a hard disk of a processor or computer.Extended history (e.g., 7 days) of a given physiological parameter maybe stored and later retrieved from the recorder, and displayed ifdesired. The processor 80 may include signal-processing algorithms toautomatically detect and alarm for abnormalities. In one embodiment, thesystem may include an alarm which may be triggered when an abnormalityis detected in a physiological parameter is detected (relative topre-set values) or when inadequate contact of sensors to make ameasurement. The system may include a manual preset of the alarmthreshold.

[0091] In one embodiment of the invention, the processing system 80 mayprocess the reflectance intensities received from the sensing system atabout 540, 580 and 640 nm to determine if a reflectance sensor 12 is inoptimal contact with an organ 100. FIG. 13G shows one example of thereflectance spectrum of white light from the surface of a deoxygenatedliver. Spectrum 200 may result from a reflectance sensor that is in goodcontact with the surface of the organ 100. Spectra 210, 220 and 230 mayresult from a sensor 12 that is not in contact with the organ 100. Theprocessing system may activate a pump 118 upon detection of a spectrumrepresenting poor sensing system contact such as 210, 220 and 230 or thelike. The processing system 80 may further control a pump 118 toincrementally pump a fluid (e.g., saline) volume into the inflatablechambers 114 while measuring changes in the spectrum after each pumpedvolume. The filling of the inflatable chambers 114 may push the sensor12 closer towards the organ 100. The processing system 80 may stop thiscontact ensure sequence upon the measurement of a spectrum representingoptimal sensor contact with the organ 100, such as about spectrum 200,or the like. A pressure sensor 120 may monitor the pressure output fromthe pump 118 and provide real-time feedback information to the pump 118and the processing system 80 to avoid excessive pressure that mayrupture the inflatable chamber 114. The processing system 80 maymemorize the volume pumped into the inflatable chamber 114, so that itcan be withdrawn later or repeated at a later time.

[0092] The system may be configured to permit a physician to be able toreview previously recorded data simultaneously while the monitor 14 isrecording. The system may include a search feature, such that aphysician may display the data segments where selected physiologicalinformation occurs, such as periods where abnormalities were detected(e.g., hypoxia or ischemia). The system may also include an alarmfeature, selectable by the user so that the system may alert the user ifan abnormality is detected. A display 18 may include a touch-screengraphic user interface 112. For example, the graphic user interface 112may permit a user to select options, including but not limited tohistory review of the information detected for a selected parameter,review of abnormal conditions, select alarm option, freeze screenoption, trace display option, sample interval selection, display mode.In one embodiment, the physician may select an interval at whichmeasurements are obtained from the tissue. This interval may vary, forexample from about 1 to 60 minutes, such as about 5 minutes.

[0093]FIG. 10 is a schematic depiction of one embodiment of a monitoringsystem 14. In one embodiment of the invention, the monitoring system 14may include a processor 80, a display 18, a fiberoptic thermometer and aspectroscopic system. The spectroscopic system may include aspectrograph and a multiplexed light source, which may be used tomeasure parameters such as the tissue perfusion, oxygenation and color.The spectrograph, lamp multiplexer 82 and/or thermometer may beconnected to a processor 80, such as by computer interface such asuniversal serial data bus (USB), digital input/output interface card(DIO), analog to digital converter (A/D), and/or RS232 serial port.

[0094] In one embodiment, a spectrometer 88 may be used to monitorphysiological parameters at a plurality of locations of the organ 100corresponding to the sensors 12 positioned at various positions alongthe drain length 20.

[0095]FIG. 11 is a schematic depiction of one embodiment of a lampmultiplexing configuration 82. An excitation optical fiber 44 a maytransmit light from a lamp 60 to a tissue 100, while a collectionoptical fiber 44 b may collect light reflected from, diffusely reflectedfrom or transmitted through the tissue 100. The system may be configuredsuch that light is emitted from one lamp 60 a for transition via anexcitation optical fiber 44 a terminating at a first position (A) of theorgan 100 for a selected duration of time, at which time no other lamp(such as 60 b or 60 c) emits light at a second (B) or third (C) positionof the organ 100 (as shown in FIG. 2A). A counter 90 may be controlledby two signal lines (i.e., clock and rest) to multiplex the spectralacquisition from different locations relative to a tissue. In oneembodiment, a plurality of optical collection fibers 44 b may connect tothe spectrometer 88, while each of the excitation optical fibers 44 amay receive light from a separate lamp 60 a-c, respectively. Hence, thespectrometer 88 may measure the spectrum of the light received via anyof the plurality of collection fibers 44 b at a selected time. In use, asensor 12 may be in the dark (i.e., inside the body) and cross talkminimized between sensors 12, such as by positioning the sensors at asuitable distance from one another along the drain length 20.

[0096] With respect to the lamp 60, an optical filter 92 may be used toremove undesired wavelength bands such as those in the ultravioletregion. A lens 94 may be used to focus light emitted by a lamp 60 intothe proximal aperture of the optical fiber 44 a. An adjustable iris (notshown) may be used to limit the light intensity to the desired levels. Avoltage regulator 96 may used to supply a constant voltage to the lamp60 and hence maintain constant irradiation levels. The processor 80 or aseparate drive may control the light on/off via its interface with themultiplexer 82.

[0097] In one embodiment, a measured spectrum of the light (such asdiffusely reflected) may be corrected for distortions caused by the darkcurrent, ambient light and/or spectral response of the system. Thespectra measured by a spectrometer 88 may be processed by the processor80 according to the known methods of diffuse reflectance spectroscopy(or transmission spectroscopy methods if applicable) for the measurementof the concentrations of oxygenated and deoxygenated hemoglobin in anorgan 100. The spectral classification methods may include peak ratios,artificial neural networks (ANN), multiple linear regression (MLR),principal component regression (PCR), and partial least squarestechniques (PLS).

[0098] In one embodiment, standard methods for converting wavelength tovisual red, green, blue (“RGB”) may be used to regenerate a colorcorresponding to the spectra collected from the organ 100 forvisualization on a display 18 of the monitoring system 14. Thewavelength to color transformation formula and the color displayalgorithm values may be calibrated using colorimetry techniques toensure that the displayed color is visually similar to the actual colorof the organ 100.

[0099] In one embodiment, spectral information obtained regarding theorgan 100 may be converted to a color index, such as a number forvisualization on a display 18 of the monitoring system 14. A numericalcolor index may be displayed to provide the physician with aquantitative color evaluation of the organ 100. This may be advantageousat least in diagnosing tissue conditions, which affect the color of theorgan 100, such as jaundice and ischemia.

[0100] A display 18 may show information, for example in a graphical,numerical or color form to a physician of user-selected physiologicalparameters including, but not limited to, tissue oxygenation, perfusion,temperature, coloration, pH and pressure. FIGS. 12A-E are schematicdiagrams depicting one embodiment of a display 18. In FIG. 12A, forexample, the display 18 may include a screen showing at least oneselected parameter for each sensor position on the organ 100 (such as“1,” “2” or “3”) over a selected time. In this example, oxygenationlevels are shown graphically over time, and corresponding patches ofcolor are depicted on a graphical symbol of the selected organ relativeto the position of each sensor 12 along the organ 100. The color patchmay be depicted as an annulus surrounding the sensor number from whichthe color is detected. In FIG. 12B, for example, the display 18 mayinclude a screen showing a plurality of different parameters for asingle sensor position upon the organ 100 over a selected time. In thisexample, oxygenation, perfusion and temperature levels are showngraphically over time, and the corresponding patch of color is depictedon a graphical symbol of the selected organ relative to the sensor 12(e.g., “2”) for which the information is being displayed. The colorpatch may be depicted as an annulus surrounding the sensor number fromwhich the color is detected. A screen indicator may mark the sensornumber from which the displayed oxygenation, perfusion and temperaturevalues were collected. The operator may select to display the parametersset of any sensor by simply clicking on the symbol of that sensor on thetouch screen.

[0101] The physiological parameter detected by each sensor 12 (such asperfusion or oxygenation of the tissue at the location of each sensor)may be visualized on a display 18 as percentage of predetermined normalvalues. For example, the display 18 shown in FIG. 12C displays theoxygenation traces of five sensors along the drain length 20 relative toa normal value.

[0102]FIG. 12C is a schematic depiction of one embodiment of a display18. A physician may select to display at least one of selectedphysiological parameters such as tissue perfusion, oxygenation, color ortemperature at each trace representative of each sensors, as shown inFIG. 12C. The display may also indicate if a sensor is not operating tocollect information (such as in trace “4”). The display may include auser input such as “Sensor Ensure” button which when activated employsthe “sensor contact ensurance system” shown in FIG. 13, if needed. Theuser may select this feature to ensure that all sensors are in goodcontact with tissue 100, where and when needed.

[0103]FIG. 12D is a schematic depiction of one embodiment of a display18. In one embodiment, the physician may select to display differentphysiological parameters measured at each sensor location, as shown inFIG. 12D. The display 18 may be configured such that multiple screenwindows may be opened to display different sensor locations at the sametime.

[0104]FIG. 12E is a schematic depiction of one embodiment of a display18. As shown in FIG. 12E, measured parameters include: blood content,abdominal secretions and bile. These parameters may be measuredoptically using standard spectrophotometric techniques. Other opticaland electrical sensors may be used to measure the pH and theconcentration of ions in the drained fluid, for example.

[0105] As depicted in this example, the surgical drain has three opticalsensors distributed along the drain length 20 for detecting fluid withinthe lumen at each of the locations. Using the “Display-Mode” slidebutton, a user may select to display all the parameters at a givensensor location or a single parameter for all sensors. The concentrationof each of the measured parameters may be determined and displayed as apercentage of the fluid mixture.

[0106] The display 18 may include a movable drain-shaped screen cursorthat may be freely oriented on a graphical symbol of the human abdomento show the physician the actual drain orientation inside the body. Thedrain-shaped cursor may be manually oriented upon the application of thedrain.

[0107] In one embodiment, it may be desirable configure the surgicaldrain 10 to maximize the contact between a sensor 12 and the organ 100.This may be advantageous at least in improving the accuracy ofmeasurements obtained from the organ 100.

[0108]FIGS. 13A & B are schematic diagrams depicting cross-sectionalviews of one embodiment of a surgical drain 10. FIGS. 13B & C areschematic depictions of side views of a surgical drain 10. In oneembodiment, the surgical drain 10 may include at least one inflatablechamber 114, such as balloons within the body of the surgical drain 10.The surgical drain 10 may further include a channel 116 in communicationwith the interior of the inflatable chamber 114. In one embodiment, apump 118 may be in communication with the channel 116 and the interiorof the inflatable chamber 114. The pump 118 may include a pressuresensor 120 in communication with the inflatable chamber 114 may be usedto control the inflation process so that the sensor 12 comes in optimalcontact with the organ 100. In one embodiment, the inflatable chamber114 may be positioned on the surgical drain upper surface 36approximately opposite a sensor 12 proximate to drain lower surface 38.The inflatable chamber 114 may be expanded by inflation, such as withsaline, air or the like such that the inflatable chamber 114 would bulgeout and create a force (F) against the adjacent tissue, as shown in FIG.13C. This force may generate a reaction force (R) that may press thesensor 12 on the drain lower surface 38 against the organ 100.

[0109] The inflatable chamber 114 may be left continuously inflatedthroughout the monitoring period, or temporarily inflated when thesensors 12 are acquiring measurements. The processor 80 may analyze theaverage intensity and/or spectral features of the reflected lightmeasured at the sensor to determine if the sensor 12 is in optimalcontact with the organ 100.

[0110]FIGS. 13E & F are schematic diagrams of a cross-sectional view ofan alternative embodiment of a surgical drain including an inflatablecompartment 114. The inflatable compartment 114 may be positioned withina central portion of the drain 10, such as within an internal rib 128.Upon inflation, forces may press the drain upper surface 36 and lowersurface 38 against tissue 100, thereby improving sensor 12 contact.

[0111]FIGS. 14A & B are schematic depictions of a bottom view and a sideview of one embodiment of a surgical drain 10. In one embodiment,sensors 12 may be positioned within or upon protrusions 122 which extendfrom the drain outer surface 26. The protrusions 122 may be integral tothe drain body 10 or attached thereto. The protrusions 122 may be madeof a transparent material. This configuration may be advantageous inincreasing the pressure with which the sensors contact an organ 100.

[0112] In use, a surgical drain 10 may be placed within a body cavityproximate to a site of trauma or surgery. The surgical drain 10 maypermit the fluid caused by tissue edema, for example, to be drained fromthe site. To position a surgical drain 10, a physician may, for example,create an incision through which the surgical drain may be implanted.Alternatively, if the patient has been opened for surgery, the drain maybe positioned proximate to the surgical site and the body closed aroundit. The surgical drain 10 may be positioned upon an organ or betweentissues of interest, and may be positioned such that sensors 12 contactdifferent regions of a tissue until monitoring is no longer needed, atwhich time the drain may be pulled out of the body. In one embodiment ofthe invention, one or more surgical drains 10 may be placedon/in/proximate to an organ 100 to monitor its condition and removedwhen monitoring is no longer desired, such as at the end of thepostoperative monitoring period.

[0113] In some embodiments, it may be desirable to stabilize theposition of the drain 10 relative to the tissue, such that the sensors12 have improved contact with the tissue 100 and/or to increase thelikelihood that measurements taken over time will be of the same orsimilar portion of the tissue 100. Therefore, in some embodiments, thesurgical drain 10 may be modified to stabilize its position relative toa monitored organ 100.

[0114] The surgical drain 10 may be actively attracted to thesurrounding organs/tissue by the continuous negative pressure (suction)in its lumen 32. The negative pressure may also draw wound fluids fromthe surgical drain 10. External suction may be actively applied to atube 40 in communication with a surgical drain 10.

[0115]FIGS. 15A & B are schematics depicting a plan view and a side viewof a surgical drain 10. In one embodiment, the surgical drain 10 mayinclude at least one anchor 124 configured for insertion into a tissue100 to stabilize the position of the surgical drain 10 within the body.The anchor 124 may be integral to the surgical drain 10 or may befabricated separately from the surgical drain 10 and connected thereto.The anchor 124 may be in the form of a biologically compatible needle,which may include a beveled distal end for insertion into a tissue 100.The direction of the insertion into a tissue 100 may be opposite to thepullout direction of the surgical drain 10 for smoother removal from thepatient.

[0116]FIG. 15C is a schematic depicting a plan view of a surgical drain10. The anchor 124 may be in the form of a loop 124 extending from thesurgical drain outer surface 26. In use, a surgeon may utilize the loopas a suture point to attach the surgical drain 10 to a tissue, such aswith a resorbable suture.

[0117]FIG. 15D is a schematic depicting a bottom view of a surgicaldrain 10. The anchor 124 may be in the form of biocompatible adhesive124, such as medical grade pressure sensitive adhesive, or fibrin gluefor adhering the surgical drain 10 to the surface of the organ 100.

[0118]FIGS. 15E & F are schematics depicting a bottom view and a sideview of a surgical drain 10, respectively. The anchor 128 may be in theform of a flap 136 which extends from the drain outer surface 26. Theflap 136 may be integral to the drain wall 30 or formed seperately andattached thereto. The flap may be formed of the same material as thedrain wall 30. The material may be selected so as to permit flexibilityof the flap 136 as it is positioned relative to the tissue 100 or as itis removed from the body 102. The flap may further include a leadingedge 130, which may be reinforced to provide a greater thickness at theleading edge 130 than at the remainder of the flap 136. The shape of theflap may be selected so as to enhance the stabilization of the drain 10relative to the organ 100, and may prevent rotation of the drain 10. Theflaps may assume any other shape including square, circular andrectangular. The flaps 136 may also include a layer of adhesive foradhering the flap to a tissue. The flaps 136 may also include sensors12, if desired.

[0119] In one embodiment, there may be flap wings 136 on both sides tostabilize the surgical drain 10 on the surface of the tissue 100. Theflap wings may increase the surface area of the drain 10 at the sensorlocation 12 and hence improve its passive adhesion to the moist surfaceof an organ. The flaps 136 may be preferably rectangular in shape withtheir apex pointing in the pullout direction of the drain 10 forsmoother removal from the patient. The flaps 136 may have edges 130 thatare reinforced against tearing by a thicker silicone layer or by anembedded thread or wire that is continuous into the drain wall 30.

[0120] Anchors 124 may be advantageous at least in preventing thesurgical drain 10 from moving relative to the organ 100 during use.Further, the anchor 124 may also hold the sensor 12 on the surgicaldrain outer surface 26 against the surface of the tissue of interest100. The form of the anchor 124 may be selected to minimize damage tothe tissue or organ to which the surgical drain 10 is attached. Further,the anchor may be selected to maximize the stability of the connectionbetween the surgical drain and the target organ, yet minimize the effortand damage caused during surgical drain removal.

[0121] In one embodiment, a surgical drain 10 may be placed in theproximity of an organ which has been transplanted, such as a liver,kidney, such that the drain length 20 is positioned longitudinally overthe organ 100. This embodiment may be advantageous at least in allowinga physician to monitor the condition of the transplanted organ from thetime of surgery through recovery to determine the condition of the organ100. A physician may use information about the condition of the organ todecide if any further intervention, such as drug treatment (such asantibiotics or immunosuppressants) or retransplantation may be required.This method of monitoring may be advantageous at least in that it mayminimize procedures to inspect the organ, enabling detection of organdysfunction at an early stage, which may allow therapeutic interventionprior to reversible damage, increase implant survival, decreasemortality rate (from infection, organ rejection), decrease the number oforgans used for retransplantation, and the additional risk and cost ofretransplantation.

[0122] While the specification describes particular embodiments of thepresent invention, those of ordinary skill can devise variations of thepresent invention without departing from the inventive concept. Forexample, it will be understood that the invention may also comprise anycombination of the embodiments described.

[0123] Although now having described certain embodiments of methods anddevices of a surgical drain, it is to be understood that the conceptsimplicit in these embodiments may be used in other embodiments as well.In short, the protection of this application is limited solely to theclaims that now follow.

We claim:
 1. A surgical drain comprising: an elongated conduitconfigured to be implanted in and to drain fluid from a body cavity, theelongated conduit including a first surface located on an outer side ofthe elongated conduit; a drain portion configured to rest against asubstantial length of tissue within the body cavity; a plurality ofdrain holes spaced along substantially the entire length of the drainportion; and a first sensing system configured to sense a physiologicalproperty of tissue proximate to the first surface, the first sensingsystem including a component that is affixed to the conduit.
 2. Thesurgical drain of claim 1, wherein the component is embedded in theconduit.
 3. The surgical drain of claim 1, wherein the componentincludes a sensor.
 4. The surgical drain of claim 1, wherein thecomponent includes an optical fiber.
 5. The surgical drain of claim 1,wherein the physiological property sensed is selected from the groupcomprising: temperature, oxygenation, perfusion, pH, NADH levels,biochemical composition, drug concentration, turgidity or pressure. 6.The surgical drain of claim 1, wherein the first sensing system detectsthe level of oxygenation of the tissue.
 7. The surgical drain of claim1, wherein the sensing system detects the hemoglobin content in thetissue.
 8. The surgical drain of claim 1, further including atransmitting element configured to deliver energy to the tissueproximate to the first surface.
 9. The surgical drain of claim 1,comprising a second sensing system configured to detect a physiologicalproperty in tissue proximate to the conduit that is different from thephysiological property sensed by the first sensing system.
 10. Thesurgical drain of claim 1, wherein the first sensing system is embeddedwithin the conduit behind material that is optically transparent. 11.The surgical drain of claim 1, further including a display configured todepict data corresponding to the physiological property sensed by thefirst sensing system.
 12. The surgical drain of claim 1, wherein theconduit includes a second surface located on an outer side of theconduit and, further including a second sensing system configured tosense the same physiological property of tissue proximate to the secondsurface.
 13. The surgical drain of claim 1, further including aprocessing system in communication with the first and second sensingsystem configured compares a difference between the physiologicalproperty sensed by the first and second sensing systems.
 14. A surgicaldrain system comprising: an elongated conduit configured to be implantedin and to drain fluid from a body cavity, the elongated conduitincluding a first surface located on an outer side of the elongatedconduit and a second surface located on an outer side of the elongatedconduit; a first sensing system configured to sense a physiologicalproperty of tissue proximate to the first outer surface; a secondsensing system configured to sense the same physiological property oftissue proximate to the second outer surface; and a processing system incommunication with the first and second sensing system that compares adifference between the physiological property sensed by the first andsecond sensing systems.
 15. A method of utilizing a surgical drain tomonitor the condition of a tissue in a body cavity, comprising:implanting a surgical drain within a body cavity in proximity to atissue to be monitored, wherein the surgical drain includes a firstsensing system configured to sense a physiological property of thetissue; receiving information from the first sensing system regarding aphysiological property of the tissue; monitoring the informationreceived from the first sensing system to evaluate the condition of thetissue over time.
 16. The method of claim 15, wherein the tissuecondition monitored is selected from the group comprising: perfusion,oxygenation, temperature, pH, NADH level, drug concentration, turgidityand pressure.
 17. The method of claim 15, comprising transmitting energyto a tissue, and receiving energy from a tissue with the first sensingsystem.
 18. The method of claim 15, comprising transmitting energythrough a tissue, and receiving energy from a tissue with the firstsensing system.
 19. The method of claim 15, further including processingthe information received from the first sensing system.
 20. The methodof claim 15, further including displaying information received from thefirst sensing system.
 21. The method of claim 15, comprising detecting alack of receipt of information from the first sensing system.
 22. Themethod of claim 15, comprising detecting a lack of contact between asensor of a sensing system and the tissue.
 23. The method of claim 15,comprising inflating an inflatable chamber associated with the surgicaldrain to decrease distance between the tissue and the surgical drain.24. The method of claim 15, comprising applying suction to a lumenwithin the surgical drain to decrease distance between the tissue andthe surgical drain.
 25. The method of claim 15, wherein implanting thesurgical drain comprises anchoring the surgical drain to a tissue withinthe body cavity.
 26. The method of claim 15, further comprising removingthe surgical drain when monitoring is not desired.
 27. A surgical draincomprising: a conduit that is bifurcated into at least two elongatedconduits to be implanted in and to drain fluid from a body cavity, thefirst elongated conduit including a first surface located on an outerside of the conduit and a second surface located on an outer side of theconduit that is substantially opposite of the first surface; the secondelongated conduit including a third surface located on an outer side ofthe conduit and a fourth surface located on an outer side of the conduitthat is substantially opposite of the first surface; a first sensingsystem configured to sense a physiological property of tissue proximateto the first surface; and a second sensing system configured to sense aphysiological property of tissue proximate to the second surface; and athird sensing system configured to sense a physiological property oftissue proximate to the third surface; and a fourth sensing systemconfigured to sense a physiological property of tissue proximate to thefourth surface.
 28. A surgical drain comprising: an elongated conduitconfigured to be implanted in and to drain fluid from a body cavity; afirst transmitting system configured to deliver spectral energy totissue proximate to the conduit; and a first sensing system configuredto detect spectral energy from the tissue proximate to the conduit. 29.The surgical drain of claim 28, further including a second sensingsystem configured to sense a physiological property from the tissueproximate to the conduit.
 30. The surgical drain of claim 29, whereinthe physiological property is selected from the group comprising:oxygenation, perfusion, temperature, pH, NADH levels, biochemicalcomposition, drug concentration, turgidity or pressure.
 31. The surgicaldrain of claim 28, wherein the conduit includes a drain portionconfigured to rest against a substantial length of tissue within thebody cavity and a plurality of drain holes spaced along substantiallythe entire length of the drain portion.
 32. The surgical drain of claim28, wherein the transmitting element and a portion of the first sensingsystem are embedded within the conduit behind optically transparentmaterial.
 33. The surgical drain of claim 28, further including adisplay configured to depict data corresponding to the spectral energydetected by the first sensing system.
 34. The surgical drain of claim33, wherein the display is configured to display a color correspondingto the spectral energy detected.
 35. The surgical drain of claim 33,wherein the display is configured to display a numerical valuecorresponding to the spectral energy.
 36. The surgical drain of claim28, further including: a second transmitting system configured todeliver spectral energy to a different tissue proximate to the conduit;and a second sensing system configured to detect spectral energy fromthe different tissue proximate to the conduit.
 37. The surgical drain ofclaim 36, further including a processing system in communication withthe first and second sensing systems that compares a difference betweenthe spectral energy sensed by the first and second sensing systems. 38.The surgical drain of claim 28, further including: a second transmittingsystem configured to deliver spectral energy to a different location ofthe same tissue than the first transmitting system; and a second sensingsystem configured to detect spectral energy from the different locationof the same tissue.
 39. The surgical drain of claim 38, furtherincluding a processing system in communication with the first and secondsensing systems that compares a difference between the spectral energysensed by the first and second sensing systems.
 40. The surgical drainof claim 28, wherein the first sensing system includes a component thatis affixed to the conduit.
 41. The surgical drain of claim 28, whereinthe component is embedded in the conduit.
 42. The surgical drain ofclaim 28, wherein the component includes a sensor.
 43. The surgicaldrain of claim 28, wherein the component includes an optical fiber. 44.A system comprising: an elongated conduit configured to be implanted inand to drain fluid from a body cavity, the elongated conduit including afirst outer surface and a second surface; a first sensing systemconfigured to detect spectral energy from tissue proximate to the firstouter surface; a processing system in communication with the firstsensing system configured to determine a color value based on thespectral energy; and a display configured to depict a colorrepresentative of tissue proximate to the first outer surface.
 45. Thesystem of claim 44, further comprising: a second sensing systemconfigured to detect spectral energy from tissue proximate to the secondouter surface; a processing system in communication with the secondsensing system configured to determine a color value based on thespectral energy; and a display configured to depict a colorrepresentative of the tissue proximate to the second outer surface. 46.The system of claim 45, wherein the processing system is configured tocompare a difference between the spectral energy detected by the firstsensing system and the second sensing system.
 47. The system of claim44, further including third sensing system configured to sense aphysiological parameter different than the first sensing system.
 48. Thesystem of claim 47, wherein the physiological property is selected fromthe group comprising: temperature, pH, NADH levels, biochemicalcomposition, drug concentration, turgidity or pressure.
 49. The systemof claim 44, further comprising a transmitting element configured todeliver energy to the tissue proximate to the first surface.
 50. Thesystem of claim 44, wherein at least portions of the first sensingsystem and transmitting element are embedded within the conduit behindoptically transparent material.
 51. The surgical drain of claim 44,wherein the conduit includes a drain portion configured to rest againsta substantial length of tissue within the body cavity and comprising aplurality of drain holes spaced along substantially the entire length ofthe drain portion.
 52. The surgical drain of claim 44, wherein the firstsensing system includes a component that is affixed to the conduit. 53.The surgical drain of claim 44, wherein the component is embedded in theconduit.
 54. The surgical drain of claim 44, wherein the componentincludes a sensor.
 55. The surgical drain of claim 44, wherein thecomponent includes an optical fiber.
 56. A system comprising: anelongated conduit configured to be implanted in and to drain fluid froma body cavity, the elongated conduit including a first outer surface anda second outer surface; a first sensing system configured to configuredto detect spectral energy from tissue proximate to the first outersurface; a processing system in communication with the first sensingsystem configured to determine a numerical color value; and a displayconfigured to depict a numerical color value representative of tissueproximate to the first outer surface.
 57. The system of claim 56,further comprising: a second sensing system configured to detectspectral energy from tissue proximate to the second outer surface; aprocessing system in communication with the second sensing systemconfigured to determine a numerical color value based on the spectralenergy; and a display configured to depict a numerical color valuerepresentative of the tissue proximate to the second outer surface. 58.The system of claim 56, wherein the processing system is configured tocompare a difference between the spectral energy detected by the firstsensing system and the second sensing system.
 59. The system of claim56, further including third sensing system configured to sense aphysiological parameter different than the first sensing system.
 60. Thesystem of claim 59, wherein the physiological property is selected fromthe group comprising: temperature, pH, NADH levels, biochemicalcomposition, drug concentration, turgidity or pressure.
 61. The systemof claim 56, further comprising a transmitting element configured todeliver energy to the tissue proximate to the first surface.
 62. Thesystem of claim 56, wherein at least portions of the first sensingsystem and transmitting element are embedded within the conduit behindoptically transparent material.
 63. The surgical drain of claim 56,wherein the conduit includes a drain portion configured to rest againsta substantial length of tissue within the body cavity and comprising aplurality of drain holes spaced along substantially the entire length ofthe drain portion.
 64. The surgical drain of claim 56, wherein the firstsensing system includes a component that is affixed to the conduit. 65.The surgical drain of claim 56, wherein the component is embedded in theconduit.
 66. The surgical drain of claim 56, wherein the componentincludes a sensor.
 67. The surgical drain of claim 56, wherein thecomponent includes an optical fiber.